A wide variety of housing assemblies are known in the art for dispensing liquids from a variety of container configurations. Many of these housings include a lever that is pushed or pulled to dispense a liquid from the container. The hygienic requirements for dispensing various liquids differ from one environment to another. In hospitals, for example, levers that are repeatedly touched by bare hands can serve to spread germs from person to person through contact with the hands. To avoid this contamination, some dispensers include a long armlever or push bar such that the liquid can be dispensed by pressing on the end of the lever with a person's elbow or forearm, such that the hands do not contact the lever. The lever then engages a pump for dispensing a quantity of liquid.
In the hospital and other environments, it is undesirable to have a lever protruding outwardly from the container that could catch people or devices passing by. In some dispensing systems, a housing is provided having an internal actuating means that engages a wall of a pouch within the housing that contains the liquid to be dispensed. In these systems, although the protruding lever is eliminated, it is difficult to achieve complete evacuation of the contents of the liquid pouch or container and contaminating air may be drawn into the container after release of the internal actuating means. A dispenser housing operable in high hygienic demanding environments that also achieves a complete evacuation of the contents of the liquid container, prevents air from being drawn thereinto, and is not overly obtrusive was disclosed in U.S. Pat. No. 6,152,330, assigned to the assignee of this application and incorporated herein in its entirety by reference.
For various reasons in some applications, it is preferable to dispense liquids in the form of a foam. Generally, foam tends to be much easier to spread than the corresponding unfoamed liquid and in addition there is much less waste due to splashing or run-off since the foam has a much higher surface tension than the unfoamed liquid. Moreover, a foam requires less liquid to produce the same or comparable cleaning power as obtained with the unfoamed liquid due to the much higher surface area of the former. To accommodate the desires of their customers, dispenser manufacturers and suppliers typically provide two separate, non-interchangeable dispensing systems, depending on whether unfoamed liquid or foam is being dispensed. Thus if a customer wishes to change from unfoamed liquid dispensing to foam dispensing (or vice versa), the customer must purchase new dispensers and have them installed in place of the previous dispensers. In many instances, such as for example, the industrial environment, healthcare environment and other environments, the number of dispensers to replace may be large thereby making such a change overly costly and inconvenient to the customer. Additionally, from a manufacturing point of view, the different, non-interchangeable designs for foam and unfoamed liquid dispensers increases tooling costs and labor costs, which lead to an increase in overall production costs.
Accordingly, it would be advantageous to not only provide a dispenser that operates in high hygienic demanding environments, achieve substantially complete evacuation of the contents of the liquid container and prevent air from being drawn thereinto, but also provide a dispenser that may be configured to dispense an unfoamed liquid or a foam in a simple, cost effective manner.